Electronic and forensics experts say information could be pulled from computers seized from Lanza's Newtown home, even if they were struck with a hammer, as some reports say.

"If he drilled holes into it, that would be a different story," said Mark Morton, a laboratory supervisor in the University of New Haven's electrical engineering department. "It depends on how much the federal government wants to spend. I believe if the federal government wants to recover data, it will get the data."

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Media: San Francisco Chronicle

Morton said techniques to recover data from severely damaged computers include dismantling and reassembling hard-drive pieces or using software owned by the Department of Defense.

Sources have said the State Police are heading the shooting investigation.

For much of the past week, their detectives and forensic experts have been reconstructing the crime scene inside the Sandy Hook school trying to pinpoint Lanza's movements and determine when and where he shot each victim.

Lanza burst into the school by shooting his way through the locked front door. He then used a military-style Bushmaster .223 semiautomatic rifle to murder the principal and school psychologist as they ran to confront him. He walked down the hallway and into two first-grade classrooms, killing six adults and 20 students.

Upon hearing police sirens and officers smashing windows to enter the school, Lanza ducked into another room and committed suicide with one of the two handguns he carried, a source said.

Peter Valentin, a retired State Police detective and forensics expert, said evidence found in the car Lanza drove to the school also could be important to the probe.

"There could be papers, notes, receipts, a backpack, a lot of personal material, particularly if that car was used by him often," he said.

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Media: San Francisco Chronicle

The car was owned by Nancy Lanza, the killer's mother. She was found dead in her bed with four .22-caliber bullet wounds in the face, a source said. A hunting rifle found at the home is believed to have been used in that murder. All of the guns found were legally purchased by Lanza's mother, who often took her son to shooting ranges.

A number of federal agencies are working with the State Police. And sources said they would be instrumental in obtaining information from Microsoft, Sony and other companies that operate online video gaming sites requiring people pay to play.

Microsoft requires its Xbox 360 owners and Sony requires PlayStation fans to purchase subscriptions to play online. Those subscriptions often are bought with a credit card and require the individual's name, screen name and an e-mail address.

Valentin said once investigators determine Lanza's game-playing user or screen names, they could determine what games, days and times he played online. They could then try to locate gamers who played with him.

Cell phones seized at the Lanza home also may contain contacts, text messages and e-mail correspondence that could prove useful, Valentin said.

He expects the full investigative report will take several months to complete.